440 kv(Primary side) and then at the receving station its step down from 440kv(primary side of the step down transformer) 33 kv.in the tranmission line,between both the primary side of the transformers the voltage is 440kv.then how the power flows in tranmission lines?
A transformer can handle power flow in either direction. The primary may be either the LV or the HV side of the transformer, likewise the secondary. By convention the primary is the side where the power flow enters the transformer and the secondary is the side where it leaves. It is NOT that the HV side is always termed primary!! In this case the generating transformer (at the generator) has a 33kV primary and 440kV secondary. This is often called a step-up transformer. The power flows from the generator through the generator transformer and into the line. It then flows along the line to the second transformer at the receiving substation. Here the HV side is primary and the LV side secondary (in other words, as you mention, it is a step-down transformer). The power is flows through this transformer and out into the further circuits. The power is (substantially) preserved at each transformation by the transformed current levels being inversely proportional to the transformed voltage levels so that V x I constant. Although nominally the voltage at each end of the line is 440kV there may (or may not) be a small difference in the voltage magnitude and there will certainly be a phase difference. If the voltage magnitudes at each end are v1 and v2 respectively and the angle between v1 and v2 is A, then the power transmitted is (v1.v2 sinA)/X where X is the impedance of the intervening line
The 440 kv is first reduced to 69Kv then down to 33kv and down to 23 kv and stepped down to 220 or 440 volts AC.
I think you will find that the primary side of the transformer is not necessarly the input side. So the 33kv is the input voltage connected to the secondary. The 440kv is the output from the primary, and the input to the second transformer. In both cases it is connected to the primary of the transformer but one transformer is used in reverse.
Gawd I don't know where people go to school to make up rubbish about the power being too high for use in homes. Just get a few facts and make the rest up. Ok When electricity is generated in a central power station the electricity needs to be transmitted many miles. The most efficient way of doing this is to use as high a voltage as possible. So at the power station a transformer is used to convert the generated voltage into a high voltage for transmission. When the electricity arrives at the destination it is transformed back down to whatever voltage the end user requires. The reason for using the high transmission voltage is to reduce resistive losses in the cables. I'll give an example Suppose we need to go 100 miles and have a resistive load of 1 ohm/mile We need to deliver 1MW down to the end of the line and the end voltage required is 100V We'll ignore the voltage drop for the example, but you can do homework to take it into account. If we transmit at 100 volts then applying W VI we need I 10^6/10^2 10^4 amps We have 10 ohms in the transmission path so resistive losses are I^2 . R (10^4)^2 . 10 10^9 Watts That is one heck of a loss! Now, if we transmit as 100kV 10^5V then our current is now 10^6/10^5 10 amps Applying I^2 . R for our resistive losses we now get 10^2 . 10 10^3 watts You can see the VAST difference that stepping up the voltage for transmission does now for the transmission loss.
